State-of-the-art digital communication switches, servers, and routers currently use multiple rows of duplex LC connector optical transceivers to meet information bandwidth and physical density needs. To be a commercially fungible product, the optical transceivers must have basic dimensions and mechanical functionality that conform to an industry standard Multi-Source Agreement (MSA) such as set forth in the Small Form Factor (SFF) committee's INF-8074i “SFP Transceiver” document. Many optical transceiver designs that comply with and add value beyond the basic mechanical functionally set forth in the MSA are possible.
FIG. 1 illustrates a standard configuration for a system 1 including an optical transceiver module 10 having a conventional delatch mechanism and a cage 12. Optical transceiver module 10 contains a transceiver that converts optical data signals received via an optical fiber (not shown) into electrical signals for an electrical switch (not shown) and converts electrical data signals from the switch into optical data signals for transmission. Cage 12 would typically be part of the switch and may be mounted in closely spaced rows above and below a printed circuit board.
When plugging module 10 into a switch, an operator slides module 10 into cage 12 until a post 14 on module 10 engages and lifts a latch tab 22 on cage 12. Module 10 then continues sliding into cage 12 until post 14 is even with a hole 24 in latch tab 22 at which point latch tab 22 springs down to latch module 10 in place with post 14 residing in hole 24. Post 14 is shaped such that an outward force on module 10 does not easily remove module 10 from cage 12. Module 10 has a delatch mechanism 30, which resides in a channel extending away from post 14. In a latched position, delatch mechanism 30 is outside cage 12, and post 14 is in hole 24. To remove module 10, delatch mechanism 30 is slid toward cage 12 until wedges 32 on delatch mechanism 30 slide under and lift latch tab 22 to a level above post 14. Module 10 can then be slid out and removed from cage 12.
Operation of delatch mechanism 30 can be awkward since removal of module 10 requires pushing in on delatch mechanism 30 while pulling out module 10. Additionally, when module 10 is in an array of modules in an optical switch, modules above module 10 will often block easy access to delatch mechanism 30, making removal of module 10 more difficult. Surrounding modules also make each module more difficult to grip.
Other module delatch mechanisms have been developed in attempts to simplify the removal procedure. One such module has a flexible strip that is attached to the module and resides under the latch tab in the latched position. To delatch the module, an operator pulls up and out on the flexible strip, and the flexible strip lifts the latch tab off the post on the module. Releasing the latch tab and removing the module in this manner requires significant upward force. For many operators, the operation of this delatch mechanism is not intuitive since pulling directly out on the flexible tab will not release the module. Additionally, in a high-density configuration, surrounding modules can make the flexible tab difficult to grip.
Another “pull-to-detach” mechanism provides the module with a post on a lever arm and a flexible handle mounted to a rod. When the flexible handle is pulled, the rod forces the lever arm to rotate and lower the post away from the cage, releasing the module from the latch on the cage. The pulling force on the flexible handle then slides the module out of the cage. Return springs that hold the lever arm and the post in position are features molded into the plastic housing. This system requires an operator to apply a great deal of force to remove the module.
FIGS. 2A and 2B illustrate cutaway bottom perspective views of a known optical transceiver module 110 having a delatch mechanism 130 that does not require excessive force to extract from a cage 120 and that is easily accessible in high density module arrangements. The module 110 and the delatch mechanism 130 are disclosed in U.S. Pat. No. 6,746,158 by the assignee of the present application and is incorporated herein by reference in its entirety.
In FIG. 2A, the delatch mechanism 130 is in a latched configuration. In FIG. 2B, the delatch mechanism 130 is in a delatched configuration. Half of cage 120 is cut away in FIGS. 2A and 2B to better show the module 110 and the delatch mechanism 130. Cage 120 includes a latch tab 122 (half of which is shown in FIG. 2A) including a hole 124 that can accommodate a post 114. Although FIG. 2A illustrates cage 120 as being isolated, cage 120 would typically be one of several substantially identical cages arranged in a dense array of cages. The delatch mechanism 130 includes an integrated structure 140 and a bail 150. Integrated structure 140 includes features such as ridges 142 and 144, spring arms 146, and wedges 148. Bail 150 is friction fit through a hole in integrated structure 140 and can be flipped down as shown in FIG. 2A to keep the bail 150 out of the way, or flipped up as shown in FIG. 2B to extend out and facilitate pulling on delatch mechanism 130 during removal of module 110. Ridges 142 and 144 also provide grip points for pulling delatch mechanism 130 when bail 150 is down or is otherwise inconvenient for gripping. An LC fiber connector (not shown) can attach to module 110 through the center of bail 150.
Spring arms 146 have ends in notches 116 in module 110. (The cut away view of FIG. 2A shows only one of notches 116, the other notch being omitted to better illustrate integrated structure 140.) Spring arms 146 flex in response to a pulling force on delatch mechanism 130 and permit a limited range of motion for delatch mechanism 130 relative to module 110. In the latched configuration shown in FIG. 2A, spring arms 146 can be uncompressed or have some spring loading, and wedges 148 reside in pockets 112 in module 110. Above wedges 148 is latch tab 122, half of which is illustrated in FIG. 2A. Through latch tab 122 is hole 124, in which post 114 resides when module 110 is latched in cage 120.
To remove the module 110 from the cage 120, an operator pulls out on delatch mechanism 130 via bail 150 or ridges 142 and/or 144. Initial pulling bends/flexes spring arms 146 and slides wedges 148 out of their respective pockets 112. As wedges 148 rise out of pockets 112, wedges 148 push up on latch tab 122. In FIG. 2B, the spring arms 146 have reached a limit of their compression and wedges 148 have lifted latch tab 122 above post 114. The spring arms 146 are at angles such that pulling on integrated structure 140 flexes spring arms 146 about their respective bases and extends the ends of spring arms 146 further into notches 116 in module 110. Accordingly, pulling more firmly engages spring arms 146 in notches 116. In the illustrated configuration of FIG. 2B, spring arms 146 contact fixed portions 147 of delatch mechanism 130 and cannot flex further. The pulling force thus acts on module 110 to slide module 110 out of cage 120.
FIG. 3 illustrates a top perspective view of a known Quad Small Form-Factor Pluggable (QSFP) optical transceiver module 160 currently used in the optical communications industry. An optical fiber cable 163 is attached to the module 160 and includes a plurality of transmit optical fibers (not shown for purposes of clarity) and a plurality of receive optical fibers (not shown for purposes of clarity). The module 160 has a housing 165 that includes a first housing portion 165a and a second housing portion 165b, which are connected together by fastening elements (not shown). The first and second housing portions 165a and 165b are typically made of cast aluminum, cast zinc, or a cast zinc alloy. A delatch device 166 allows the module housing 165 to be delatched from a cage (not shown) to enable the module housing 165 to be removed from the cage. A flexible plastic pull tab 167 is connected on its proximal end 167a to the delatch device 166. When a user pulls on the distal end 167b of the pull tab 167 in the direction indicated by arrow 168, slider portions 166a and 166b of the delatch device 166 move to a limited extent in the direction indicated by arrow 168 (only slider portion 166a can be seen in FIG. 3). This movement of the slider portions 166a and 166b causes outwardly curved ramps 166a′ and 166b′ of the slider portions 166a and 166b, respectively, to press outwardly against respective catch features on the cage (not shown) to allow the housing 165 to be retracted from the cage.
With respect to FIG. 1, because the module 1 does not have a bail or a pull tab, removing it from the cage 12 when arranged in a densely-packed array or cages can be very challenging. With reference to FIGS. 2A and 2B, although the delatch mechanism 130 works well with regard to delatching and removing the module 110 from the cage 120, the bail 150 is fairly short, which can make the task of removing the module 110 from the cage 120 difficult in situations where many such modules are positioned adjacent one another in a densely-packed array. In addition, the module 110 cannot even be removed from the cage 120 without first unplugging the optical fiber cables (not shown) from the cage 120 to enable the bail 150 to be moved to the delatch position. This makes it more difficult to use the module 110 in hot-pluggable environments. Another problem associated with some optical transceiver modules that use bail-type delatching configurations is that the bail is often coupled to the module housing by pins or screws that can damage the housing, resulting in lower yield. With respect to FIG. 3, the pins 171 that are used to attach the flexible plastic pull tab 167 to the module housing 165 sometimes damage the housing 165, resulting in lower yield.
Accordingly, a need exists for a delatching device that has a configuration that enables a user to easily pull an optical transceiver module from a cage in a densely-packed array and that overcomes the aforementioned disadvantages. A need also exists for a delatching device that is well-suited for use in hot-pluggable environments and which does not require removal of the optical fiber cables in order to delatch the optical transceiver module from a cage. A need also exists for a delatching device that is attachable to the optical transceiver module without the need for pins or screws that can damage the module housing and reduce production yield.